The invention relates to a lung demand valve having a whistle and a method of upgrading a lung demand valve by attaching a whistle to a lung demand valve.
A lung demand valve (LDV) is typically used with breathing apparatus in order to control the delivery of breathable gas from a source of breathable gas, such as a gas cylinder, to a user operating in a hazardous environment. An LDV typically comprises a flexible diaphragm that responds to pressure changes associated with inhalation or expiration by a user, so as to open and close a valve and thereby control the flow of breathable gas. A first side of the diaphragm is exposed to ambient pressure and the second side of the diaphragm is exposed to the pressure within the facemask.
During use of the breathing apparatus, the amount of breathable gas may diminish, and therefore the pressure of the breathable gas may reduce. A low pressure may indicate that the source of breathable gas is running out. Accordingly, it is important for users of breathing apparatus to monitor the pressure of the source of breathable gas so that they can evacuate the hazardous environment before the source of breathable gas completely runs out.
It is known to provide self-contained breathing apparatus with a pressure gauge having a warning device that generates an audible or visual alarm when the pressure of the source of breathable gas drops below a minimum. In other arrangements the pressure of the source of breathable gas may be remotely monitored and warnings may be provided by radio communication with a banksman or an operator monitoring the gas supply.
Whilst these known warning arrangements may be satisfactory in some circumstances, users may fail to notice when their warning device has been activated, or may fail to realise that a warning relates to their equipment and not that of another person operating in the same hazardous environment. This may be especially problematic in noisy and/or dirty environments.
It is therefore desirable to provide an improved warning arrangement for use with breathing apparatus.